In the manufacture process of a Liquid Crystal display (LCD), firstly, the prepared mother panel needs to be cut so as to obtain panels of desired dimensions, and then, panels of corresponding dimensions (comprising the cell-assembled panels) are placed into a panel box. After that, the robot arm may be used to successively take out panels from the panel box from the bottom up.
The panel box is provided with slots for carrying the panels, by which the panels can be stacked within the panel box layer by layer.
Currently, mapping sensors corresponding to the slots in respective layers are generally used to detect whether there is a panel at the corresponding level, when the vertical spacing between the slots in the panel box is 55 mm. For example, from the bottom up, the slots in the panel box are numbered as a first level, a second level, . . . , and so on, according to the levels at which the slots are located. When the robot arm arrives at the 20th level and it is known that no panel presents at the 20th level through the mapping sensor, the robot arm will directly step over the 20th level and take out panels from the 21th level.
However, in order for a better utilization of space, it is desired to reduce the spacing between the slots in the panel box. For example, the vertical spacing between the slots in the panel box is 10 mm. In such case, the spacing is too small to mount mapping sensors, so that the robot arm detects the presence of a panel from the undermost slot each time, and then performs the action of taking out the panel. Even worse, when no panel presents, the robot arm needs to repeat the taking-out action for 10 times and then notify that no panel is detected, and the robot arm does not perform the action for detecting a panel in the next slot until an operator manually clicks on the button of “detection of next slot”. During the process, when there's no panel in a slot at a certain level, the robot arm can not learn whether a panel presents at this level, thus the process of taking out panels, as a whole, is relatively time-consuming.